A woman casts her ballot on Sunday at a school used as a polling station in Purmamarca in northern Argentina.

BUENOS AIRES, Argentina  First lady Cristina Fernandez claimed victory in Argentina's presidential election Sunday, with early results and exit polls suggesting she had avoided a runoff and become the first woman elected to the post.

Fernandez's husband, President Nestor Kirchner, is credited with Argentina's rebound from a 2001 economic collapse, and much of her support is due to his popularity.

She has been compared to U.S. Sen. Hillary Rodham Clinton, who like her is a lawyer and senator who soldiered alongside a husband as he rose from small-state governor to his nation's presidency.

"We have won amply," she proclaimed, Kirchner standing at her side. "But this, far from putting us in a position of privilege, puts us instead in a position of greater responsibilities and obligations."

Supporters jumped up and down and embraced one another.

"I'm so excited," screamed Maria Isabel Francia, a 50-year-old street merchant. "Cristina is going to pull us out of poverty!"

Her challengers were trying to force her into a Nov. 25 runoff. She needed 40 percent of the vote, with a lead of more than 10 percent over her nearest rival, to win outright.

Of the first 10 percent of polling places reporting, Fernandez had 42 percent of the vote, compared with 21 percent for former Economy Minister Roberto Lavagna and 18 percent for Elisa Carrio. Eleven others split the rest.

Six independent television networks, a private radio station and an opposition newspaper reported their exit polling indicated Fernandez has easily won a first-round victory. Five of the news organizations released their numbers, giving Fernandez between 42 and 46 percent of the vote, with advantages of 19 to 23 percentage points over Carrio.

But no opposition candidates conceded defeat, and Carrio spokesman Matias Mendez said seven parties had filed a complaint alleging that ballots were missing or stolen in Buenos Aires province, the country's most populous.

Electoral officials denied any irregularities, but a judge extended voting by an hour in the capital after many of Argentina's 12,700 polling stations opened late. A representative of the ruling party was arrested on suspicion of trying to vote twice.

The next president, who begins a four-year term on Dec. 10, faces challenges including high inflation, an energy shortage and rampant crime. And the legacy of the economic crisis can still be seen in high unemployment and widespread poverty in a country that a century ago ranked among the world's 10 richest.

Fernandez, 54, refused to debate and spent much of the campaign abroad in photo-ops with world leaders. Her chic European dresses and designer bags drew comparisons with "Evita" Peron, another fashion-conscious and politically influential Argentine first lady.

Fernandez, who built her own independent career as her husband rose to power, has rejected comparisons to both Clinton and Evita.

She boasts that she won her first national election, as senator for Santa Cruz province, when Kirchner was a mere state official  the governor. She is now a senator for powerful Buenos Aires province.

The first couple voted early in Santa Cruz, before heading back to the capital to await the outcome. Fernandez told the crowd of reporters that voting was especially joyful for her because she grew up under the 1976-83 dictatorship.

"I'm part of a generation that grew up in a country in which nobody could say anything, so we value this in a very special way," she said.

Voters were also filling dozens of House and Senate seats and nine governorships. Exit polls indicated Vice President Daniel Scioli won the governorship of Buenos Aires province, the country's second most powerful post.

Argentina's 27.1 million registered voters are required by law to cast ballots, and one couple showed up early after a night of partying in a car festooned with "just married" signs. The bride wore a white wedding dress as she filled out her ballot.